<template>
  <div class="todo-footer" v-show="total">
    <label>
      <input type="checkbox" v-model="isAll"/>
    </label>
    <span>
      <span>已完成{{doneTotal}}</span> / 全部{{total}}
    </span>
    <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
  </div>
</template>

<script>
  export default {
    name: 'MyFooter',
    props:['todos'],
    computed:{
      // 总的todo数量
      total(){
        return this.todos.length
      },
      // 已完成todo数量
      doneTotal(){
        // 数组filter后长度 写法
        //return this.todos.filter(todo => todo.done === true).length

        // reduce写法
        /*const x = this.todos.reduce((pre, current) => {
          console.log('@@@',pre, current)
          return pre + (current.done ? 1 : 0)
        },0)
        return x*/

        // reduce简写
        return this.todos.reduce((pre,todo) => pre + (todo.done ? 1 : 0), 0)
      },
      isAll:{
        get(){
          return this.total === this.doneTotal && this.total > 0
        },
        set(value){
          this.$emit('isAllTodo',value)
        }
      }
    },
    methods:{
      clearAll(){
        this.$emit('clearAllTodo')
      }
    }
  }
</script>

<style scoped>
/*footer*/
.todo-footer {
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}

.todo-footer label {
  display: inline-block;
  margin-right: 20px;
  cursor: pointer;
}

.todo-footer label input {
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}

.todo-footer button {
  float: right;
  margin-top: 5px;
}

</style>